TWI548504B - Slicing method of semiconductor single crystal ingot - Google Patents

Description

Slicing method for semiconductor single crystal ingot

The present invention relates to a method of slicing a semiconductor single crystal ingot such as a single crystal ingot to form a semiconductor single crystal wafer such as a single crystal wafer.

The single crystal cutting method disclosed in the prior art is a method in which a single crystal member having a split surface is moved relative to a processing tool that cuts the single crystal member, and the processing tool is cut into a single crystal member. The crystal member is cut along the predetermined cut surface, and the cutting direction of the processing tool is set to be perpendicular to the normal line of the orthogonal line of the predetermined cut surface and the split surface, and the single crystal member discharged by the cutting tool is cut. The direction of the cutting direction is inclined, and the inclination angle of the cutting direction with respect to the normal direction is set to an angle at which the single crystal member cutting energy rate by the processing tool is extremely large (see, for example, Patent Document 1). In the single crystal cutting method, the split planes of the single crystal member appear orthogonal lines A and B on the predetermined cutting surface. Further, the cutting directions in which the cutting energy rate is extremely large are respectively inclined from the vertical normal lines P and Q to the side of the cutting direction of the cuttings or counterclockwise with respect to the orthogonal lines A and B, respectively, and only the rotation angles θ ₁ and θ are respectively inclined. ₂ , θ ₃ , θ ₄ , θ ₅ , θ ₆ , θ ₇ , θ ₈ in the Z ₁ , Z ₂ , Z ₃ , Z ₄ , Z ₅ , Z ₆ , Z ₇ , Z ₈ directions. Further, when the single crystal member is lithium niobate, θ ₁ is 24 degrees, θ ₂ is 7 degrees, θ ₃ is 16 degrees, θ ₄ is 8 degrees, θ ₅ is 20 degrees, and θ ₆ is 17 degrees, θ. ₇ is 16 degrees and θ ₈ is 5 degrees.

The single crystal cutting method configured as described above is a method of cutting a single crystal member with respect to a predetermined cut surface located on a single crystal and perpendicular to a line perpendicular to an orthogonal line of the predetermined cut surface and the split surface. The chip discharge direction is set to a positive rotation angle, and the cutting ability determined by the crystallographic property of the single crystal member having the positive rotation angle and the pressure contact force between the single crystal member and the processing tool is extremely large. Further, since the single crystal member is cut, the cutting and removing energy rate is particularly improved, and the cutting processing time which takes a long time can be shortened. Further, since excessive strain is not applied to the single crystal member during processing, the wafer to be cut does not cause warpage or warpage.

On the other hand, it is disclosed that the single crystal ingot is cut into a single crystal ingot while the single crystal ingot is moved relative to the cutter, and the single crystal ingot is sliced along the predetermined cut surface to form a single crystal ingot. The single crystal cutting method in which the crystal orientation is set to <111> and the slicing is performed in parallel in the direction of the crystal line (see, for example, Patent Document 2).

In the single crystal cutting method configured as described above, the crystal orientation of the single crystal ingot is determined to be <111>, and the cutting machine is used in the state in which the cutting direction of the cutting machine is aligned with the direction of the crystal axis of the single crystal ingot. By slicing the single crystal ingot in a direction parallel to the above-mentioned wafer line, the wafer can be cut and separated with little bending and warpage, and the cutting efficiency can be remarkably improved. That is, the split surface of the giant single crystal ingot is usually the (111) plane, and the direction of the slice of the single crystal ingot is corrected along the crystal line generated due to the difference in the degree of development of the crystal face, so that it is extremely difficult to obtain the wafer to be cut. An ideal wafer that is bent and warped.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 1-15363 (Application No. 1-15, No. 3, No. 31 of the specification - No. 32 of the same column, No. 32 of the specification, No. 42 to No. 4, No. 6 , column 6, line 39 of the manual - column 7, line 8, line 1 ~ figure 3)

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2005-231248 (Patent Application No. 1, paragraph [0007], [0016])

However, in the single crystal cutting method described in the above Patent Document 1, there is no provision for the angle between the predetermined cut surface and the split surface of the single crystal member, and it is impossible to know that the wafer is cut after the single crystal member is cut. What is the difference in the amount of warpage? Further, in the single crystal cutting method shown in the above Patent Document 1, the cutting position of the single crystal member is deviated from the split surface (i.e., with respect to the orthogonal lines A and B appearing on the predetermined cut surface). 5 to 25 degrees, such a small angle will not fully improve the wafer warpage. Moreover, in the single crystal cutting method shown in the above-mentioned Patent Document 1, since the excessive strain is not applied to the single crystal member in the cutting process of the single crystal member, the wafer to be cut does not bend. Warping, but there is also the problem of how to control the amount of wafer warpage. On the other hand, in the single crystal cutting method shown in the above-mentioned Patent Document 2, since the single crystal ingot is sliced along the crystal line, the bending and warpage of the wafer are less likely to occur, but the crystal cannot be controlled. The problem of rounded curvature.

The object of the present invention is to provide: not only can reduce the amount of wafer warpage, It is also possible to accurately control the wafer warpage amount to a desired amount of a semiconductor single crystal ingot slicing method.

In the method for slicing a semiconductor single crystal ingot according to the first aspect of the present invention, the columnar semiconductor single crystal ingot is used only under a predetermined rotation angle state centering on the crystal axis of the ingot different from the central axis of the ingot cylinder. The method of slicing a semiconductor single crystal ingot in which the ingot is sliced by the cutting device in this state is characterized in that the amount of warpage of the wafer sliced by the cutting device is quantified. Determine the predetermined angle of rotation when the holding tool then holds the ingot.

According to a second aspect of the present invention, in the invention of the first aspect, the correlation relationship between the wafer warpage amount change and the predetermined rotation angle change is further determined in advance, and the predetermined rotation angle is determined from the correlation relationship.

According to a third aspect of the invention, in the invention according to the first aspect, the predetermined rotation angle when the ingot is held by the holding tool is determined so that the amount of warpage of the wafer sliced by the cutting device is minimized.

According to a fourth aspect of the present invention, in the invention according to the first aspect, the amount of warpage of the wafer sliced by the cutting device is increased by a predetermined amount, and the wafer is warped after the epitaxial layer is formed on the surface of the wafer. The mode in which the curvature is minimized determines the predetermined angle of rotation when the holding tool is used to hold the ingot.

According to a fifth aspect of the invention, in the invention of the first aspect, the rotation reference portion is further formed in the ingot, and the vertical line drawn from the crystal axis of the ingot toward the rotation reference portion is used as a reference line with respect to the reference The predetermined rotation angle of the line The degree is in the range of 35 to 75 degrees, 105 to 145 degrees, 215 to 255 degrees, or 285 to 325 degrees.

In the semiconductor single crystal wafer according to the sixth aspect of the present invention, the columnar semiconductor single crystal ingot is used in a state in which the predetermined rotation angle is rotated about a crystal axis of the ingot different from the central axis of the ingot cylinder. Then, a semiconductor single crystal wafer obtained by slicing an ingot by a cutting device in this state is formed, and a rotation reference portion is formed in the ingot, and is drawn from the crystal axis of the ingot toward the rotation reference portion. When the lower vertical line is the reference line, the predetermined rotation angle with respect to the reference line is in the range of 35 to 75 degrees, 105 to 145 degrees, 215 to 255 degrees, or 285 to 325 degrees.

In the slicing method according to the first aspect of the present invention, before the cylindrical semiconductor single crystal ingot is held by the holding means of the cutting device, the ingot is first set to be centered on the crystal axis of the ingot different from the central axis of the cylinder. The rotation is performed, and then the ingot is rotated by a predetermined rotation angle around the crystal axis, and then held by the holding tool. At this time, since the predetermined rotation angle around the crystal axis is determined by the amount of warpage of the wafer sliced by the cutting device, the wafer warpage amount after the ingot slicing can be accurately performed. Control the amount required.

In the slicing method according to the second aspect of the present invention, the correlation between the warpage amount change and the predetermined rotation angle change is determined in advance, and the predetermined rotation angle is determined from the correlation, so that the ingot can be sliced. The wafer warpage amount is accurately controlled to the required amount.

The slicing method according to the third aspect of the present invention The amount of warpage of the wafer to be sliced is minimized, and the predetermined rotation angle around the crystal axis of the ingot is determined, so that the amount of warpage of the wafer after the ingot slicing can be reduced.

In the dicing method according to the fourth aspect of the present invention, the amount of warpage of the wafer to be sliced by the cutting device is a predetermined amount, and the amount of warpage of the wafer after the epitaxial layer is formed on the surface of the wafer is minimized. The predetermined rotation angle centered on the crystal axis of the ingot is determined, so that the wafer warpage amount after the ingot is sliced and the epitaxial layer is formed on the wafer surface can be reduced.

The slicing method according to the fifth aspect of the present invention is characterized in that a perpendicular line drawn from the crystal axis of the ingot toward the rotation reference portion is used as a reference line, and a predetermined rotation angle with respect to the reference line is set at 35 to 75 degrees, 105 to 145. In the range of 215 to 255 degrees or 285 to 325 degrees, the amount of warpage of the wafer after the ingot is cut can be approximately the required amount.

In the semiconductor single crystal wafer according to the sixth aspect of the present invention, a perpendicular line drawn from the crystal axis of the ingot toward the rotation reference portion is used as a reference line, and a predetermined rotation angle with respect to the reference line is set to 35 to 75 degrees, 105 to Ingots in the range of 145 degrees, 215 to 255 degrees, or 285 to 325 degrees, the amount of warpage of the wafer obtained by slicing is approximately the required amount.

11, 12‧‧‧1st and 2nd main scroll wheels

13‧‧‧矽Single crystal ingot (semiconductor single crystal ingot)

13a‧‧‧Cylinder central axis

13b‧‧‧ Crystallization axis

13c‧‧‧ Orientation plane (rotation reference)

13d‧‧‧ baseline

13e‧‧‧劈面

13f‧‧‧ wire marking

14‧‧‧ Keeping tools

14a‧‧‧Slice table

14b‧‧‧Working board

16‧‧‧Wire sawing device (cutting device)

17‧‧‧Second roller

18‧‧‧Steel wire

19‧‧‧ Lifting device

19a‧‧‧Support members

19b‧‧‧Horizontal components

21‧‧‧around the bobbin

22‧‧‧Winning bobbin

23‧‧‧ wafer

56‧‧‧ Band saw device (cutting device)

51, 52‧‧‧1st and 2nd pulleys

51a, 52b‧‧‧1st and 2nd vertical axes

53‧‧‧blade

53a‧‧‧Leather

53b‧‧‧Cutting inserts

53c‧‧‧Line moving part

61, 62‧‧‧1st and 2nd blade fixtures

Fig. 1 is a front view showing an essential part of a state in which a single crystal ingot is sliced by a wire of a wire saw machine using the slicing method according to the first embodiment of the present invention.

Fig. 2 is a perspective view showing an important part of the ingot state in which the ingot is cut by the wire of the wire saw device.

In Fig. 3, (a) is a three-dimensional schematic view of a wafer in which a steel sheet is cut by a steel wire, a splitting surface is formed in a cutting direction, and a wire is deviated in the direction of the splitting surface; Warped cut-off wafer side view.

In Fig. 4, (a) is a three-dimensional schematic view of a wafer in which the ingot is not cut in the cutting direction by the steel wire, and the wire is in a straight line in the cutting direction; (b) Side view of the wafer after warping that has occurred.

In Fig. 5, (a) is a front view of the ingot of the steel wire in which the split surface of the ingot is parallel to the surface of the ingot; (b) the longitudinal section of the ingot in which the split surface of the ingot is inclined to the crystal axis of the ingot Fig. (c) is a longitudinal sectional view of the ingot with the steel wire deviated toward the cleavage plane.

In Fig. 6, (a) is a front view of the ingot of the steel wire marked with the split surface of the ingot parallel to the surface of the ingot; (b) a longitudinal sectional view of the ingot in which the ingot split surface is parallel to the crystal axis state of the ingot; (c) A longitudinal section of the ingot in which the steel wire advances in a straight line in the cutting direction.

In Fig. 7, (a) is a structural diagram in which the central axis of the cylinder of the ingot coincides with the crystal axis, and the steel wire state is extended in a direction perpendicular to the central axis of the cylinder and the crystal axis; (b) the cylindrical center of the ingot The ingot structure diagram in which the axis does not coincide with the crystal axis; (c) is a structural diagram in which the steel wire state is extended in a direction perpendicular to the crystal axis that does not coincide with the central axis of the cylinder.

Fig. 8 is a perspective view showing an essential part of a state in which an ingot is sliced by a band saw of a band saw device by using the slicing method according to the second embodiment of the present invention.

Fig. 9 is a graph showing changes in the warpage amount of each wafer when the ingot rotation angles of the first embodiment and the comparative example 1 are changed.

Fig. 10 is a graph showing changes in the amount of warpage of each wafer when the ingot rotation angle of the second embodiment is changed.

11 is a wafer of Example 3, Comparative Example 2, and Comparative Example 3, each of which is actually The distribution of the amount of warpage to the amount of warpage of the target.

Fig. 12 is a wafer warpage amount distribution diagram of the wafer immediately after the formation of the epitaxial layer, the wafer of Example 4 in which the epitaxial layer was formed, and the comparative example 4 in which the epitaxial layer was formed.

Next, the form in which the present invention is applied will be described based on the drawings. As shown in FIGS. 1 and 2, a wire saw device is used to slice and cut the single crystal ingot 13. The wire saw device 16 is provided with first and second main rollers 11 and 12 that are disposed in parallel with each other in the same horizontal plane, and are disposed below the first and second main rollers 11 and 12 and are provided on a single secondary roller 17 at an intermediate position between the first and second main rollers 11 and 12, a wire 18 wound around the first and second main rollers 11 and 12 and the single secondary roller 17, and a holding tool 14 Lifting device 19 (Figs. 1 and 2). Further, the outer circumferential surfaces of the first and second main rollers 11, 12, and the single sub-roller 17 are spaced apart from each other in the axial direction of the respective rollers 11, 12, and 17 (that is, at the axes of the respective rollers 11, 12, and 17). A plurality of annular grooves (not shown) extending in the circumferential direction are formed in the direction just apart from the interval between the thicknesses of the sliced wafers. The wire 18 is wound around a long strip wound around the bobbin 21 (Fig. 2), and the wire 18 wound from the winding bobbin 21 is compliant with the first and second main rollers 11, 12, The ring grooves on one end side of the single sub-roller 17 are sequentially accommodated in the respective ring grooves on the other end side, and are formed in a slightly inverted triangular shape on the rollers 11, 12, and 17 and spirally wound and stretched. It is then taken up on the take-up bobbin 22 (Fig. 2).

The holding tool 14 is provided with a dicing table 14a following the ingot 13, and a workpiece plate 14b holding the dicing table 14a. The slicing table 14a is composed of The ingot 13 is formed of the same material or glass, ceramic, carbon, resin, or the like. When considering the cost surface and ease of molding, carbon, resin, or the like is often used. Further, an epoxy resin, a thermoplastic wax or the like is used as the adhesive, and the workpiece plate 14b is mainly formed of SUS. Further, the lifting device 19 includes a support member 19a extending in the vertical direction, and a horizontal member 19b that is attached to the support member 19a so as to be lifted and held, and the holding tool 14 is held under the front end. Thereby, the ingot 13 which is formed by the holding tool 14 can be raised and lowered by the lifting device 19.

A method of slicing the single crystal ingot 13 using the wire saw device 16 will be described. First, the wire 18 is wound around the first and second main rollers 11 and 12 and the single sub-roller 17. Thereby, the wire 18 horizontally stretched between the first and second main rollers 11 and 12 in the wire 18 is horizontally moved by the rotation of the first and second main rollers 11 and 12 and the single sub-roller 17 . Next, on the lower surface of the front end of the horizontal member 19b of the lifting device 19, the ingot 13 is placed on the slicing table 14a attached via the workpiece plate 14b. Here, the method of following the ingot 13 to the slicing table 14b will be described in detail. In the case of a cylindrical ingot, it is hardly an ideal state in which the central axis of the cylinder coincides with the crystal axis (Fig. 7(a)), and almost the actual state in which the central axis of the cylinder is not coincident with the crystal axis (Fig. 7 b)). Therefore, the ingot 13 is first designed to be rotatable about the crystal axis 13b of the ingot 13 different from the central axis 13a of the cylinder (Fig. 7(c)). Further, the crystal axis 13b of the ingot 13 can be detected by an X-ray angle which is irradiated and reflected by the crystal face. Next, the ingot 13 is centered on the crystal axis 13b, and the state in which the predetermined rotation angle is rotated is continued on the above-described slicing table 14b.

At this time, the predetermined rotation angle around the crystal axis 13b is determined by the amount of warpage of the wafer 23 obtained by slicing the wire saw device 16. The amount is determined. Preferably, the determination determines the correlation of the change in the warpage amount of the relevant wafer 23 with respect to the change in the predetermined rotation angle in advance, and determines the predetermined rotation angle from the correlation. Further, the perpendicular line drawn from the crystal axis 13b of the ingot 13 toward the orientation flat 13c is the reference line 13d, and it is preferable to set the predetermined rotation angle θ (Figs. 3 and 4) to 35 to 75 with respect to the reference line 13d. Degree, 105~145 degrees, 215~255 degrees, or 285~325 degrees. However, when the slice table 14a is subsequently placed on the ingot 13, in order to avoid the orientation flat 13c, it is preferable to set the predetermined rotation angle θ in the range of 35 to 75 degrees or 285 to 325 degrees with respect to the reference line 13d. More preferably in the range of 40 to 60 degrees or 300 to 320 degrees. Here, the reason why the predetermined rotation angle θ is limited to the above-described range with respect to the reference line 13d is that the wire 18 is easily displaced in the direction of the cleavage surface 13e of the ingot 13, and the ingot 13 is sliced to obtain the wafer 23. The amount of warpage change will become larger.

Next, the ingot 13 is placed above the wire 18 horizontally stretched between the first and second main rollers 11 and 12, and passes through the respective central axes of the first and second main rollers 11 and 12. Between the lead lines, the crystal axis 13b of the ingot 13 moves almost parallel to the respective central axes of the first and second main rollers 11, 12 (Figs. 1 and 2). At this time, the vertical plane including the crystal axis 13b of the ingot 13 is orthogonal to the direction in which the steel wire 18 between the first and second main rollers 11 and 12 extends (Fig. 7(c)). In other words, the crystal axis of the ingot is made orthogonal to the plane formed by the wire 18 between the first and second main rollers 11 and 12 and the direction in which the ingot is cut by the wire 18. Further, in this state, the ingot 13 is sliced by moving the ingot 13 in the vertical direction and moving to a position across the wire 18 moving in the horizontal direction. Thereby, the amount of warpage of the wafer 23 after slicing the ingot 13 can be accurately controlled to a desired amount.

Here, even if the split surface 13e of the ingot 13 is parallel to the wire mark 13f on the surface of the wafer 23, the amount of warpage of the wafer 23 obtained by slicing the ingot 13 is different. The reason will be described with reference to Figs. 3 to 6 . As shown in Fig. 5 (a) and Fig. 6 (a), even if the split surface 13e of the ingot 13 is parallel to the wire mark 13f on the surface of the ingot 13, the split surface 13e of the ingot 13 is as shown in Fig. 5 ( b) is shown as being inclined to the crystal axis 13b of the ingot 13, and as shown in Fig. 6(b) parallel to the crystal axis 13b of the ingot 13. On the other hand, when the split surface 13e of the ingot 13 is inclined to the crystal axis 13b of the ingot 13 (Fig. 5(b)), if the ingot 13 is sliced, the wire 18 is directed to the direction of the dotted arrow of Fig. 3 and Fig. 5 The cutting direction indicated by the solid arrow direction of (c) is more likely to deviate from the direction of the solid arrow in FIG. 3(a) and the direction indicated by the direction of the broken arrow in FIG. 5(c) (ie, the direction of the split surface 13e). However, when the split surface 13e of the ingot 13 is parallel to the crystal axis 13b of the ingot 13, (Fig. 6(b)), if the ingot 13 is sliced, the steel wire 18 is directed to the dotted line of Fig. 4(a). The direction of the arrow and the direction of the solid arrow in Fig. 6(c) are less likely to deviate from the cutting direction, and proceed in a straight line toward the cutting direction. As a result, even if the split surface 13e of the ingot 13 is parallel to the wire mark 13f on the surface of the ingot 13 (Fig. 5(a)), if the split surface 13e of the ingot 13 is inclined to the crystal as shown in Fig. 5(b) The crystal axis 13b of the ingot 13 is sliced to obtain the wafer 23, and warp appears as shown in Fig. 3(b). On the other hand, even if the split surface 13e of the ingot 13 is parallel to the wire mark 13f on the surface of the ingot 13 (Fig. 6(a)), if the split surface 13e of the ingot 13 is parallel to the square as shown in Fig. 6(b) The crystal axis 13b of the ingot 13 is sliced to obtain the wafer 23, and there is no warpage as shown in Fig. 4(b). Further, even if the cleavage surface 13e of the ingot 13 is not parallel to the crystal axis 13b of the ingot 13, as shown in Fig. 6(b), it is at a nearly parallel angle (for example, 35 to the crystal axis 13b of the ingot 13). 75 degrees), then cut The wafer 23 obtained by the sheet is less prone to warpage.

On the other hand, the predetermined rotation angle centering on the crystal axis 13b of the ingot 13 can be determined in such a manner that the amount of warpage of the wafer 23 is minimized by slicing the ingot by the wire saw device 16. For example, when the crystal axis 13b of the ingot 13 is <111>, a perpendicular line drawn from the crystal axis 13b toward the orientation flat 13c is referred to as a reference line 13d, and a predetermined rotation angle θ is set with respect to the reference line 13d. (Fig. 3 and Fig. 4) The setting of the range of 35 to 75 degrees can reduce the amount of warpage of the wafer 23 after the ingot 13 is sliced. Further, the predetermined rotation angle centering on the crystal axis 13b of the ingot 13 may be equal to the amount of warpage of the wafer 23 sliced by the wire saw device 16, and formed on the surface of the wafer 23. The amount of warpage of the wafer 23 after the epitaxial layer (not shown) is determined to be the smallest. For example, when the crystal axis 13b of the ingot 13 is <111>, a perpendicular line drawn from the crystal axis 13b toward the orientation flat 13c is referred to as a reference line 13d, and a predetermined rotation angle θ is set with respect to the reference line 13d ( 3 and 4), in the range of 35 to 75 degrees, the amount of warpage of the wafer 23 after the ingot 13 is sliced and the epitaxial layer having a thickness of 0.1 to 200 μm is formed on the surface of the wafer 23 can be reduced.

Further, in the above embodiment, the wire cutting device is used as the cutting device, but the band saw device 56 shown in Fig. 8 may be used as the cutting device. The band saw device 56 includes first and second pulleys 51 and 52 that are disposed at predetermined intervals with the first and second vertical axes 51a and 52b as rotation centers, and are suspended from the first and second pulleys 51. , the strip blade 53 on the 52. The blade 53 is composed of a ring-shaped endless belt 53a formed of a metal band plate, and a cutting insert 53b formed by electrodepositing diamond particles on the lower edge of the belt 53a by electroplating. The rotation of the first pulley 51 is configured. Driven between the first and second pulleys 51, 52 The circular motion is performed in one direction. Further, in the blade 53, the first and second blades that suppress the vibration of the linearly moving portion 53c are disposed on both side portions (linearly moving portions) 53c that move linearly in one direction between the first and second pulleys 51 and 52. Fixtures 61, 62. The first and second blade holders 61 and 62 are formed by sandwiching the blade 53 from the both sides by a carbon shoe-shaped plate (not shown), and the blade 53 is held in contact with the posture parallel to the cutting direction. On the lower side of the linear moving portion 53c of the blade 53, the single crystal ingot 13 is disposed orthogonally to the blade 53, and the first and second pulleys 51, 52 are placed in a state in which the blade 53 is circumferentially moved in one direction. The cutting blade 53b, which is formed by the linear moving portion 53c of the blade 53, is cut in the vertical direction to cut the ingot 13. In addition, the holding tool which hold|maintains the ingot 13 is not shown in FIG.

Further, in the above embodiment, the semiconductor single crystal ingot may be, for example, a single crystal ingot, but may be a tantalum carbide (SiC) single crystal ingot, a gallium arsenide (GaAs) single crystal ingot, or a sapphire single crystal ingot. Further, in the first and second embodiments, the cutting device is exemplified by a wire saw device and a band saw device, but may be an ID saw (Inner Diameter saw). Further, in the above embodiment, the predetermined rotation angle around the crystal axis of the ingot is determined by using a perpendicular line drawn from the crystal axis of the ingot toward the orientation plane as a reference line, but it is also possible to draw from the crystal axis of the ingot toward the notch. The lower vertical line is the reference line and determines the predetermined rotation angle centered on the crystal axis of the ingot. Further, in place of the rotation reference portion of the orientation flat or the notch, the predetermined rotation angle around the crystal axis of the ingot can be determined with the perpendicular line drawn from the crystal axis of the ingot toward the rotation reference portion as a reference line.

[Examples]

Next, the embodiments of the present invention and comparative examples will be described in detail.

<Example 1>

As shown in FIGS. 1 and 2, a cylindrical single crystal ingot 13 having a diameter of 150 mm and a crystal axis of <111> was prepared. The crystal axis 13b of the ingot 13 different from the cylindrical central axis 13a of the ingot 13 is centered, and is held by the holding tool 14 while rotating only a predetermined rotation angle. At this time, the crystal axis 13b of the ingot 13 is detected by the X-ray angle which is irradiated and reflected by the crystal face. Further, it is determined that the ingot 13 follows a predetermined rotation angle when the tool 14 is held. Further, when the vertical line drawn from the crystal axis 13b of the ingot 13 toward the orientation flat 13c is the reference line 13d, the predetermined rotation angle is set as the rotation angle θ with respect to the reference line 13d (Figs. 3 and 4). . Specifically, the ingot 13 is placed above the wire 18 horizontally stretched between the first and second main rollers 11 and 12 of the wire saw device 16, and passes through the first and second main rollers 11, 12 Between the lead lines of the respective central axes, the crystal axis 13b of the ingot 13 moves almost parallel to the respective central axes of the first and second main rollers 11, 12 (Figs. 1 and 2). At this time, the vertical plane including the crystal axis 13b of the ingot 13 is orthogonal to the direction in which the steel wire 18 between the first and second main rollers 11 and 12 extends (Fig. 7(c)). Then, by inverting the ingot 13 in the vertical direction and moving it to the position of the wire 18 moving in the horizontal direction, the ingot 13 is sliced, and the wafer 23 is obtained. The predetermined rotation angle θ is adjusted within a predetermined range, and the ingot 13 is sliced in the same manner as described above to form the wafer 23. These wafers 23 are set to the first embodiment.

<Comparative Example 1>

The ingot was placed in the same manner as in Example 1 except that the crystal axis of the ingot different from the central axis of the ingot was rotated and rotated by an arbitrary rotation angle, and then held by a holding tool. Slice and make crystal circle. These wafers were set as Comparative Example 1.

<Test 1 and evaluation>

The wafer warpage amounts of Example 1 and Comparative Example 1 were measured. The wafer warpage amount is a plane formed on the back surface of the wafer at a position 3 mm from the outer periphery of the wafer toward the inner side, and is assumed to be formed by three planes spaced apart by 120 degrees around the crystal axis of the wafer, and is set. The maximum value of the wafer warpage measured from this plane. The result is shown in Figure 9.

As is apparent from Fig. 9, in Comparative Example 1, the wafer warpage amount is small within a predetermined rotation angle range, but the wafer warpage amount is increased outside the predetermined rotation angle range, and the wafer warpage amount of the first embodiment is relatively large. All are small.

<Example 2>

The same ingot was used as the ingot of Example 1, but three ingots of other batches were sliced to form wafers. However, when the ingot was held in the holding tool, the wafer was produced in the same manner as in Example 1 except that the predetermined rotation angles around the crystal axis of the ingot were set to 51 degrees, 55 degrees, and 56 degrees, respectively. . These wafers were set to Example 2.

<Test 2 and evaluation>

The wafer warpage amount of Example 2 was measured in the same manner as in Test 1 described above. Further, from the wafer measurement values of Example 1 and Comparative Example 1 measured in Test 1, an approximate curve of the change in the warpage amount of the wafer with respect to the change in the rotation angle of the ingot was obtained. The relationship between the wafer warpage amount of the above-described second embodiment and the above-described approximate curve is as shown in FIG.

As is apparent from Fig. 10, the wafer warpage amount of Example 2 almost coincides with the above-described approximate curve. As a result, it was confirmed that when the ingot was followed by the holding tool, By setting the predetermined rotation angle around the ingot to a predetermined range, the wafer warpage can be accurately controlled.

<Example 3>

An ingot having a diameter of 150 mm and a crystal axis of <111> was sliced to prepare 200 wafers. However, in order to make the warpage amount of the wafer obtained by the slicing a target warpage amount, the predetermined rotation angle which is rotated around the crystal axis of the ingot is set to 50 degrees when the ingot is next to the holding tool. A wafer was produced in the same manner as in Example 1 except for the rest. These wafers were set to Example 3.

<Comparative Example 2>

The ingot of the same shape as the ingot of Example 3 was sliced to prepare 200 wafers. However, when the ingot was placed on the holding tool, the wafer was produced in the same manner as in Example 1 except that the predetermined rotation angle around the crystal axis of the ingot was set to 25 degrees. These wafers were set as Comparative Example 2.

<Comparative Example 3>

The ingot of the same shape as the ingot of Example 3 was sliced to prepare 200 wafers. However, when the ingot is next to the holding tool, the predetermined rotation angle that is rotated about the crystal axis of the ingot is set to 25 degrees, and the ingot is cut at the 1/2 speed of Comparative Example 2, and the rest are A wafer was produced in the same manner as in Example 1. These wafers were set as Comparative Example 3.

<Test 3 and evaluation>

The wafer warpage amounts of Example 3 and Comparative Examples 2 and 3 were measured in the same manner as in Test 1 described above. The result is shown in FIG.

As is apparent from FIG. 11, the wafer of Comparative Example 2 has a large variation in the direction in which the amount of warpage increases with respect to the amount of warpage of the target. The wafer of Comparative Example 3 fluctuated around the target warpage amount and caused a large fluctuation. The wafer of Example 3 was the target (target) despite the cutting speed equivalent to that of Comparative Example 2. The amount of warpage changes and changes little at the center.

<Example 4>

An ingot having a diameter of 125 mm and a crystal axis of <111> was sliced to prepare 43 wafers. However, in order to reduce the amount of warpage of the wafer when an epitaxial layer is formed on the surface of the wafer obtained by slicing, the ingot is formed in such a manner that the warpage amount of the wafer immediately after the slicing becomes the target warpage amount. Next, a wafer was produced in the same manner as in Example 1 except that the predetermined rotation angle around which the crystal axis of the ingot was rotated was set to 50 degrees while the tool was being held. These wafers were set to Example 4.

<Comparative Example 4>

The ingot having the same shape as the ingot of Example 4 was sliced to prepare 51 wafers. However, when the amount of warpage of the wafer when the epitaxial layer is formed on the surface of the wafer is obtained by slicing, it is not determined that the ingot is rotated around the crystal axis of the ingot when the ingot is held by the ingot. A wafer was produced in the same manner as in Example 1 except that the rotation angle was set to 25 degrees. These wafers were set as Comparative Example 4.

<Test 4 and Evaluation>

The wafer warpage amount after the epitaxial layer was formed on the wafer surfaces of Example 4 and Comparative Example 4 was measured in the same manner as in Test 1 described above. The result is shown in FIG. In addition, in FIG. 12, the data immediately after cutting is the wafer warpage amount of the wafer of Comparative Example 4, and the wafer immediately after the ingot was cut, before the epitaxial layer was formed on the wafer surface.

It can be seen from FIG. 12 that the amount of warpage of the wafer after the epitaxial layer is formed in Comparative Example 4 is relatively large, and in contrast, the wafer of the fourth embodiment after forming the epitaxial layer is warped. The volume is small.

11, 12‧‧‧1st and 2nd main scroll wheels

13‧‧‧矽Single crystal ingot (semiconductor single crystal ingot)

14‧‧‧ Keeping tools

14a‧‧‧Slice table

14b‧‧‧Working board

16‧‧‧Wire sawing device (cutting device)

17‧‧‧Second roller

18‧‧‧Steel wire

19‧‧‧ Lifting device

19a‧‧‧Support members

19b‧‧‧Horizontal components

Claims (5)

A method for slicing a semiconductor single crystal ingot, wherein a cylindrical semiconductor single crystal ingot is centered on a crystal axis of the ingot different from a central axis of the ingot cylinder, and is held by a holding tool only under a predetermined rotation angle state. In this state, the ingot is sliced by a cutting device, and the amount of warpage of the wafer sliced by the cutting device is quantified, and it is determined that the holding tool then holds the ingot. a predetermined rotation angle; and a rotation reference portion is formed in the ingot, and when a perpendicular line drawn from the crystal axis of the ingot toward the rotation reference portion is used as a reference line, the predetermined rotation angle with respect to the reference line is 35~75 degrees, 105~145 degrees, 215~255 degrees, or 285~325 degrees. The method for slicing a semiconductor single crystal ingot according to the first aspect of the invention, wherein the correlation relationship between the warpage amount change and the predetermined rotation angle change is determined in advance, and the predetermined relationship is determined from the correlation relationship. Rotation angle. The method for slicing a semiconductor single crystal ingot according to the first aspect of the invention, wherein the amount of warpage of the wafer sliced by the cutting device is minimized, and when the holding tool is used to hold the ingot, The above predetermined rotation angle. The method for slicing a semiconductor single crystal ingot according to the first aspect of the invention, wherein the amount of warpage of the wafer sliced by the cutting device is a predetermined amount, and the crystal is formed on the surface of the wafer after the epitaxial layer is formed. Round warp is the most In a small manner, the above-described predetermined rotation angle when the ingot is held by the above holding tool is determined. A semiconductor single crystal wafer in which a cylindrical semiconductor single crystal ingot is held by a holding tool while rotating at a predetermined rotation angle centering on the crystal axis of the ingot different from the central axis of the ingot cylinder, In the state in which the ingot is sliced by the cutting device, the rotation reference portion is formed in the ingot, and the perpendicular line drawn from the ingot crystal axis toward the rotation reference portion is used as a reference line. The predetermined rotation angle with respect to the reference line is in the range of 35 to 75 degrees, 105 to 145 degrees, 215 to 255 degrees, or 285 to 325 degrees.